mirror of
https://github.com/qpdf/qpdf.git
synced 2024-06-25 23:02:38 +00:00
Add new method QPDFParser::parseRemainder
The new method is temporarily an (almost) complete copy of parse, which is temporarily (almost) unchanged.
This commit is contained in:
m-holger
parent
db6ab9cbfa
commit
5a1bf035f9
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@ -38,11 +38,343 @@ QPDFParser::parse(bool& empty, bool content_stream)
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std::shared_ptr<QPDFObject> object;
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bool set_offset = false;
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std::vector<StackFrame> stack{{input, st_top}};
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// std::vector<StackFrame> stack{{input, st_top}};
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stack.clear(); // NEW
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stack.emplace_back(input, st_top); // NEW
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bool done = false;
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bool b_contents = false;
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bool is_null = false;
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auto* frame = &stack.back();
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frame = &stack.back(); // CHANGED
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while (!done) {
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bool indirect_ref = false;
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is_null = false;
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object = nullptr;
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set_offset = false;
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if (!tokenizer.nextToken(*input, object_description)) {
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warn(tokenizer.getErrorMessage());
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}
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++good_count; // optimistically
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switch (tokenizer.getType()) {
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case QPDFTokenizer::tt_eof:
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if (stack.size() > 1) {
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warn("parse error while reading object");
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}
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if (content_stream) {
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// In content stream mode, leave object uninitialized to indicate EOF
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return {};
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}
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// QTC::TC("qpdf", "QPDFParser eof in parse");
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warn("unexpected EOF");
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return {QPDF_Null::create()};
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case QPDFTokenizer::tt_bad:
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// QTC::TC("qpdf", "QPDFParser bad token in parse");
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if (tooManyBadTokens()) {
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return {QPDF_Null::create()};
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}
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is_null = true;
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break;
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case QPDFTokenizer::tt_brace_open:
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case QPDFTokenizer::tt_brace_close:
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// QTC::TC("qpdf", "QPDFParser bad brace");
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warn("treating unexpected brace token as null");
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if (tooManyBadTokens()) {
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return {QPDF_Null::create()};
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}
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is_null = true;
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break;
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case QPDFTokenizer::tt_array_close:
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if (frame->state == st_array) {
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if (stack.size() < 2) {
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throw std::logic_error("QPDFParser::parseInternal: st_stop encountered with "
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"insufficient elements in stack");
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}
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object = QPDF_Array::create(std::move(frame->olist), frame->null_count > 100);
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setDescription(object, frame->offset - 1);
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// The `offset` points to the next of "[". Set the rewind offset to point to the
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// beginning of "[". This has been explicitly tested with whitespace surrounding the
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// array start delimiter. getLastOffset points to the array end token and therefore
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// can't be used here.
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set_offset = true;
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stack.pop_back();
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frame = &stack.back();
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} else {
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// QTC::TC("qpdf", "QPDFParser bad array close");
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warn("treating unexpected array close token as null");
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if (tooManyBadTokens()) {
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return {QPDF_Null::create()};
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}
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is_null = true;
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}
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break;
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case QPDFTokenizer::tt_dict_close:
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if (frame->state == st_dictionary) {
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if (stack.size() < 2) {
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throw std::logic_error("QPDFParser::parseInternal: st_stop encountered with "
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"insufficient elements in stack");
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}
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// Convert list to map. Alternating elements are keys. Attempt to recover more or
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// less gracefully from invalid dictionaries.
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std::set<std::string> names;
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for (auto& obj: frame->olist) {
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if (obj) {
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if (obj->getTypeCode() == ::ot_name) {
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names.insert(obj->getStringValue());
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}
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}
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}
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std::map<std::string, QPDFObjectHandle> dict;
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int next_fake_key = 1;
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for (auto iter = frame->olist.begin(); iter != frame->olist.end();) {
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// Calculate key.
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std::string key;
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if (*iter && (*iter)->getTypeCode() == ::ot_name) {
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key = (*iter)->getStringValue();
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++iter;
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} else {
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for (bool found_fake = false; !found_fake;) {
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key = "/QPDFFake" + std::to_string(next_fake_key++);
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found_fake = (names.count(key) == 0);
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// QTC::TC("qpdf", "QPDFParser found fake", (found_fake ? 0 : 1));
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}
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warn(
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frame->offset,
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"expected dictionary key but found non-name object; inserting key " +
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key);
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}
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if (dict.count(key) > 0) {
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// QTC::TC("qpdf", "QPDFParser duplicate dict key");
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warn(
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frame->offset,
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"dictionary has duplicated key " + key +
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"; last occurrence overrides earlier ones");
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}
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// Calculate value.
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std::shared_ptr<QPDFObject> val;
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if (iter != frame->olist.end()) {
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val = *iter;
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++iter;
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} else {
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// QTC::TC("qpdf", "QPDFParser no val for last key");
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warn(
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frame->offset,
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"dictionary ended prematurely; using null as value for last key");
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val = QPDF_Null::create();
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}
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dict[std::move(key)] = std::move(val);
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}
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if (!frame->contents_string.empty() && dict.count("/Type") &&
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dict["/Type"].isNameAndEquals("/Sig") && dict.count("/ByteRange") &&
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dict.count("/Contents") && dict["/Contents"].isString()) {
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dict["/Contents"] = QPDFObjectHandle::newString(frame->contents_string);
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dict["/Contents"].setParsedOffset(frame->contents_offset);
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}
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object = QPDF_Dictionary::create(std::move(dict));
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setDescription(object, frame->offset - 2);
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// The `offset` points to the next of "<<". Set the rewind offset to point to the
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// beginning of "<<". This has been explicitly tested with whitespace surrounding
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// the dictionary start delimiter. getLastOffset points to the dictionary end token
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// and therefore can't be used here.
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set_offset = true;
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stack.pop_back();
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frame = &stack.back();
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} else {
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// QTC::TC("qpdf", "QPDFParser bad dictionary close");
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warn("unexpected dictionary close token");
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if (tooManyBadTokens()) {
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return {QPDF_Null::create()};
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}
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is_null = true;
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}
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break;
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case QPDFTokenizer::tt_array_open:
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case QPDFTokenizer::tt_dict_open:
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if (stack.size() > 500) {
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// QTC::TC("qpdf", "QPDFParser too deep");
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warn("ignoring excessively deeply nested data structure");
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return {QPDF_Null::create()};
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} else {
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b_contents = false;
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stack.emplace_back(
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input,
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(tokenizer.getType() == QPDFTokenizer::tt_array_open) ? st_array
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: st_dictionary);
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frame = &stack.back();
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return parseRemainder(content_stream); // NEW
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continue;
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}
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case QPDFTokenizer::tt_bool:
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object = QPDF_Bool::create((tokenizer.getValue() == "true"));
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break;
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case QPDFTokenizer::tt_null:
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is_null = true;
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++frame->null_count;
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break;
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case QPDFTokenizer::tt_integer:
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object = QPDF_Integer::create(QUtil::string_to_ll(tokenizer.getValue().c_str()));
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break;
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case QPDFTokenizer::tt_real:
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object = QPDF_Real::create(tokenizer.getValue());
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break;
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case QPDFTokenizer::tt_name:
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{
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auto const& name = tokenizer.getValue();
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object = QPDF_Name::create(name);
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if (name == "/Contents") {
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b_contents = true;
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} else {
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b_contents = false;
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}
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}
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break;
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case QPDFTokenizer::tt_word:
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{
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auto const& value = tokenizer.getValue();
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auto size = frame->olist.size();
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if (content_stream) {
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object = QPDF_Operator::create(value);
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} else if (
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value == "R" && frame->state != st_top && size >= 2 && frame->olist.back() &&
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frame->olist.back()->getTypeCode() == ::ot_integer &&
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!frame->olist.back()->getObjGen().isIndirect() && frame->olist.at(size - 2) &&
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frame->olist.at(size - 2)->getTypeCode() == ::ot_integer &&
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!frame->olist.at(size - 2)->getObjGen().isIndirect()) {
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if (context == nullptr) {
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// QTC::TC("qpdf", "QPDFParser indirect without context");
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throw std::logic_error("QPDFObjectHandle::parse called without context on "
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"an object with indirect references");
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}
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auto ref_og = QPDFObjGen(
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QPDFObjectHandle(frame->olist.at(size - 2)).getIntValueAsInt(),
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QPDFObjectHandle(frame->olist.back()).getIntValueAsInt());
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if (ref_og.isIndirect()) {
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// This action has the desirable side effect of causing dangling references
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// (references to indirect objects that don't appear in the PDF) in any
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// parsed object to appear in the object cache.
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object = context->getObject(ref_og).obj;
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indirect_ref = true;
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} else {
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// QTC::TC("qpdf", "QPDFParser indirect with 0 objid");
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is_null = true;
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}
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frame->olist.pop_back();
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frame->olist.pop_back();
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} else if ((value == "endobj") && (frame->state == st_top)) {
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// We just saw endobj without having read anything. Treat this as a null and do
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// not move the input source's offset.
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is_null = true;
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input->seek(input->getLastOffset(), SEEK_SET);
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empty = true;
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} else {
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// QTC::TC("qpdf", "QPDFParser treat word as string");
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warn("unknown token while reading object; treating as string");
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if (tooManyBadTokens()) {
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return {QPDF_Null::create()};
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}
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object = QPDF_String::create(value);
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}
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}
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break;
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case QPDFTokenizer::tt_string:
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{
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auto const& val = tokenizer.getValue();
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if (decrypter) {
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if (b_contents) {
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frame->contents_string = val;
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frame->contents_offset = input->getLastOffset();
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b_contents = false;
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}
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std::string s{val};
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decrypter->decryptString(s);
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object = QPDF_String::create(s);
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} else {
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object = QPDF_String::create(val);
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}
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}
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break;
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default:
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warn("treating unknown token type as null while reading object");
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if (tooManyBadTokens()) {
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return {QPDF_Null::create()};
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}
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is_null = true;
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break;
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}
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if (object == nullptr && !is_null) {
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throw std::logic_error("QPDFParser:parseInternal: unexpected uninitialized object");
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}
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switch (frame->state) {
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case st_dictionary:
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case st_array:
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if (is_null) {
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object = null_oh;
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// No need to set description for direct nulls - they probably will become implicit.
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} else if (!indirect_ref && !set_offset) {
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setDescription(object, input->getLastOffset());
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}
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set_offset = true;
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frame->olist.push_back(object);
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break;
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case st_top:
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done = true;
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break;
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}
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}
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if (is_null) {
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object = QPDF_Null::create();
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}
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if (!set_offset) {
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setDescription(object, frame->offset);
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}
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return object;
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}
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QPDFObjectHandle
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QPDFParser::parseRemainder(bool content_stream)
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{
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// This method must take care not to resolve any objects. Don't check the type of any object
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// without first ensuring that it is a direct object. Otherwise, doing so may have the side
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// effect of reading the object and changing the file pointer. If you do this, it will cause a
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// logic error to be thrown from QPDF::inParse().
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const static std::shared_ptr<QPDFObject> null_oh = QPDF_Null::create();
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// QPDF::ParseGuard pg(context);
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// empty = false;
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std::shared_ptr<QPDFObject> object;
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bool set_offset = false;
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// std::vector<StackFrame> stack{{input, st_top},};
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bool done = false;
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bool b_contents = false;
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bool is_null = false;
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frame = &stack.back(); // CHANGED
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while (!done) {
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bool indirect_ref = false;
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@ -280,7 +612,7 @@ QPDFParser::parse(bool& empty, bool content_stream)
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// not move the input source's offset.
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is_null = true;
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input->seek(input->getLastOffset(), SEEK_SET);
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empty = true;
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// empty = true;
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} else {
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QTC::TC("qpdf", "QPDFParser treat word as string");
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warn("unknown token while reading object; treating as string");
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@ -50,6 +50,9 @@ class QPDFParser
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int null_count{0};
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};
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QPDFObjectHandle
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parseRemainder(bool content_stream);
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bool tooManyBadTokens();
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void warn(qpdf_offset_t offset, std::string const& msg) const;
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void warn(std::string const& msg) const;
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@ -61,6 +64,8 @@ class QPDFParser
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QPDFObjectHandle::StringDecrypter* decrypter;
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QPDF* context;
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std::shared_ptr<QPDFValue::Description> description;
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std::vector<StackFrame> stack;
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StackFrame* frame;
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// Number of recent bad tokens.
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int bad_count = 0;
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// Number of good tokens since last bad token. Irrelevant if bad_count == 0.
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